[Markedz]

Hello all, I am new to the forum but I do have my whits about me. I have a 1970 C20 Longhorn with factory A/C and I am in the process of rebuilding the heating / Air Conditioning system myself. I have some information as well as some questions. In the two images of the manuals above one has a water valve that says "Open" when vacuum applied and the other is "Closed". I believe this does matter when talking about the vacuum head. When the controls are in the heat position the vacuum head is closed (Not allowing for vacuum). This would not work with a a water valve that is "Open" when vacuum applied. My vacuum head only has 2 ports, not three. The summation is: if the controls are in the "Heat position" and the vacuum head is open then you must have a water valve that opens under vacuum. If the vacuum head is closed when in the heat position then you need a water valve that is closed under vacuum. The direction of the flow for the water valve does matter. The intake side of the water valve is the curved tube, the outlet is the straight tube. You can use a garden hose to verify, it will not work if hooked up wrong. Anybody have a part number for a water valve that is closed when vacuum applied?